This study will explore whether a novel pooled-survey methodology can be employed to improve inferences about ECE environments in child obesity and related nutritional and physical activity antecedents. The specific attention to the relative effectiveness of HS compared to subsidized care and other ECE environments is designed to inform federal policy by the CCDF in the research area of Child and Family Wellbeing. A critical barrier to previous research on ECE environments and child obesity has been the inability of existing surveys to meet the high demands of both sample power and substantive detail. This study will employ statistical methods to evaluate whether a nationally-representative sample of children followed in the Early Childhood Longitudinal Surveys Birth Cohort (ECLS-B) can be appropriately matched with a nationally representative sample of children enrolled in HS who were followed in the 2006 Head Start Family and Child Experiences Survey (FACES). This study will then use quasi-experimental methods to examine the effectiveness of HS relative to subsidized care and other ECE environments in altering the trajectory of child outcomes. This study will identify vulnerable subpopulations, evaluate potential bias from selection into ECE environments, and explore differences by the duration, intensity and quality of the care environment. The study findings and methodological insights will be disseminated in peer-reviewed papers, a policy brief, and presentations to researchers, practitioners, and policymakers, and will have implications for the potential enhancement and expansion of successful early care strategies to prevent child obesity and obesity disparities.